Study of the active cardiovascular of a-terpineol in rats - in vivo and in vitro Experimental Models

The essential oils are volatiles organic constituents found in aromatic plants, which present several monoterpenes. a-terpineol is an important chemical constituent of the essential oil of many plants.. Studies have demonstrated some biologic activities such as antifungal and antispasmodic. In the present work the cardiovascular effects of a-terpineol were investigated in normotensive rats. Male Wistar rats (250-350 g) were anaesthetized and polyethylene catheters were inserted into the low abdominal aorta and inferior vena cava for blood pressure measurements and administration of drugs. Arterial pressure and heart rate were measured by using a pressure transducers coupled to a computer set and CVMS software. Isolated superior mesenteric rings (1-2 mm) were suspended by cotton threads for isometric tension recordings in Tyrode s solution (37°C, gassed with 95% O2 and 5% CO2), under 0.75g resting tension. In normotensive non-anaesthetized rats (n=6), a-terpineol (1, 5, 10, 20, 30 mg/Kg i.v., randomly) injections produced hypotension (-8,6 ± 2,25; - 18,35 ± 4,35; -33,25±6,0; -51,2±4,5 e -49,5±6,5 mmHg, n=6 , respectively followed by tachycardia (44,6±5,3; 24,5±8,4; 109,8±7,3; 113,2±12,4 e 35,8±14,0 bpm, n=6, respectively). However, hypotensive and tachycardic responses were significantly attenuated after L-NAME (20 mg/Kg ,i.v.) administration i.v (-1,5±0,6; -4,9±2,0; - 6,9±2,8; -22,0±9,0 e -22,1±9,0 mmHg, n=4). In intact isolated rat mesenteric rings a- terpineol (10-12 10-5M) induced concentration-dependent relaxation of the contractions induced by phylephrine (10μM) [Emax=62.41±13.79%]. After endothelium removal the vasorelaxant elicited by a-terpineol was significantly attenuated [Emax= 20.08±4.95]. Similar results were obtained in the presence LNAME 100 or 300 μM, a competitive antagonist of NOS, hydroxocobalamin 30 μM, a NO scavenger or ODQ 10μM, a selective inhibitor of soluble guanylyl cyclase [Emax= 18.33± 3.85% Emax= 23.24± 3.93% Emax= 23.49±7.05 Emax= 20.79 ± 1.06% respectively, p